For packaging semiconductors such as IC and electronic components using IC, an injection tray, a vacuum-formed tray, a magazine, an embossed carrier tape, etc. are used. An embossed carrier tape is mainly used in view of efficient packaging and mounting of electronic components. For such a packaging container, one having an electrically conductive filler dispersed is used to prevent electronic components such as IC from being destroyed by static electricity. As the electrically conductive filler, carbon black is widely used to achieve a stable surface resistivity uniformly at a low cost.
An electrically conductive packaging container comprising a thermoplastic resin having carbon black dispersed has such a problem that mechanical strength and moldability tend to decrease by addition of carbon black. Further, by friction between an electronic component as a content and the packaging container, the surface of the packaging container may be abraded, whereby the resin containing carbon black on the surface is separated to contaminate the electronic component. As a method of solving the former problem, it is proposed to employ a multilayer structure and to add carbon black to the surface layer (for example, Patent Documents 1 and 2). As a method of solving the latter problem of separation of carbon, it is proposed to add an olefin resin or a styrene thermoplastic elastomer to the surface layer containing carbon black (for example, Patent Documents 3 and 4). However, miniaturization and high integration of electronic components are in rapid progress, and as a packaging container for such electronic components, a packaging container such as an embossed carrier tape, which has higher mechanical strength, which is less likely to cause contamination and which is further excellent in dimensional stability, has been desired.
As a method to achieve such an object, for example, Patent Document 5 proposes a sheet comprising, as a substrate layer, an acrylonitrile/butadiene/styrene copolymer resin and/or a polystyrene resin, and as a surface layer thereof, a polycarbonate resin composition containing carbon black laminated on the substrate layer, and a packaging container using the sheet, such as a carrier tape. Further, Patent Document 6 proposes a sheet comprising, as a substrate layer, a polycarbonate resin, and as a surface layer thereof, a polycarbonate resin composition containing carbon black laminated on the substrate layer, and a packaging container using the sheet, such as a carrier tape. However, an embossed carrier tape comprising an electrically conductive sheet using a polycarbonate resin for the surface layer has low sealing properties with a cover tape to be used as a covering material when an electronic component is packaged, and so as to obtain sufficient sealing strength, the sealing time should be prolonged, or the sealing temperature should be increased, and such is difficult to cope with high speed packaging.
Patent Document 1: JP-A-57-205145
Patent Document 2: JP-A-62-18261
Patent Document 3: JP-A-9-76424
Patent Document 4: JP-A-9-76425
Patent Document 5: JP-A-2003-512207
Patent Document 6: JP-A-2002-67258